1. Field of the Invention
The present invention relates to a detachable insert-type cutting tool in which a head member is detachably mounted on a head portion of a holder and a cutting insert is also detachably attached to an insert seat formed on the head member.
2. Description of the Related Art
For example, Published Japanese Translation No. H09-510149 of the PCT International Application has proposed a tool which is able to communicate with coolant supply means for supplying a coolant to the vicinity of a cutting edge, as a tool for cutting the bottom of a hole formed on a workpiece. The tool is provided with a fluid inlet orifice arranged near an adaptor end portion and a fluid outlet orifice arranged at the leading end of an adaptor mounting portion above an insert retaining portion, in which a coolant hole extending substantially along an adaptor is formed at an adaptor mounting portion (head member) between the fluid inlet orifice and the fluid outlet orifice. The fluid inlet orifice is coupled with a coolant duct array of a tool shank (holder) to communicate with the coolant supply means. In this case, the coolant duct array of the tool shank extends along the tool shank and ends with a transverse coolant hole located at a tool-shank retaining portion in an area between the rear end of the retaining portion and a screw hole. The transverse coolant hole has at least one outlet portion so as to align with the fluid inlet orifice of the adaptor.
The inventor and others of the present invention have also proposed in Japanese Published Unexamined Patent Application No. H07-227702 a groove-forming tool which is provided with a tip (cutting insert), a holder for mounting the tip, a supporter mounted on the holder to support the tip, and a clamp piece mounted on the holder to press the tip toward the supporter, thereby fixing the tip. An ejection port for ejecting a cutting fluid toward a flank of the tip in a groove subjected to groove-forming and a cutting fluid supply hole for supplying the cutting fluid to the ejection port are formed on the supporter of the groove-forming tool. An ejection port for ejecting the cutting fluid toward a rake surface of the tip in a groove and a cutting fluid supply hole for supplying the cutting fluid to the ejection port are formed on the clamp piece. Then, the cutting fluid supply holes on the supporter and the clamp piece communicate with a cutting fluid supply hole formed on the holder at parts on which the supporter and the clamp piece are in contact with the holder. Further, Published European Patent Application EP 1495821 has also proposed a tool in which a coolant is ejected toward a cutting edge.
In the detachable insert-type cutting tool described in Published Japanese Translation No. H09-510149 of the PCT International Application and that described in Japanese Published Unexamined Patent Application No. H07-227702, a coolant supplied via a coolant hole formed on a holder is ejected toward a cutting edge through coolant holes and cutting fluid supply holes formed on an adaptor mounting portion (head member), a supporter and a clamp piece. However, the adaptor mounting portion, the supporter, the clamp piece and others are needed for drilling by using a drill or the like to result in an increase in production cost. In particular, as found in the tool for groove-forming a workpiece described in Published Japanese Translation No. H09-510149 of the PCT International Application and Japanese Published Unexamined Patent Application No. H07-227702, when the size of a part to be drilled is restricted depending on the width of a groove formed on the workpiece, it is difficult to drill into the workpiece. There are also fears that a failure in forming a sufficiently large ejection port may result in a failure in securing a necessary quantity of coolant supplied to a cutting edge.
Further, in the detachable insert-type cutting tool described in Published Japanese Translation No. H09-510149 of the PCT International Application and that described in Japanese Published Unexamined Patent Application No. H07-227702, a coolant hole formed along a direction of the center axis (longitudinal direction) of a holder in the shape of a shaft is once bent in a radial direction with respect to the center axis thereof, thereby communicating with an adaptor mounting portion, a supporter, a coolant hole on a clamp piece, and a cutting fluid supply hole. Then, the coolant hole and the cutting fluid supply hole are also bent and formed so as to eject a coolant toward a cutting edge. The holder, the adaptor mounting portion, the supporter and the clamp piece are drilled from an outer circumferential surface in the direction of the center axis and in the radial direction and, thereafter, openings of unnecessary holes formed on the outer circumferential surface must be sealed with a plug or the like. The above-described problem is also found in the tool described in Published European Patent Application EP 1495821. In particular, a tool for cutting an inner circumferential surface of a hole has a cutting edge which protrudes in a radial direction with respect to the center axis of a holder. Therefore, a coolant hole must be bent from a direction of the center axis of the holder to a direction at which the cutting edge protrudes and this tool always entails the above-described problem.
The present invention has been made under the above-described circumstances, an object of which is to provide a detachable insert-type cutting tool in which at least a head member does not need to be drilled with a drill or the like to reduce production costs and secure a necessary supply quantity of coolant and, in particular, when used as a tool for cutting an inner surface of a hole, a coolant is supplied in a sufficient quantity to a cut site, thus making it possible to secure cooling and lubrication.